Eg: sand from sand + water mixture
2) CRYSTALLISATION
Eg: copper(II)sulphate from impure copper(II)sulphate mixture
* Crystallisation is usually carried out with filtration.
3) DISTILLATION
Defn: to obtain pure liquid from a solution of solute
Eg: water from sea water
4) FRACTIONAL DISTILLATION
Defn: to separate liquids with different boiling points
Eg:
(i) ethanol from ethanol(78'C) + water(100'C)
(ii) crude oil into petrol, kerosene, lubicating oil etc
(iii) air into nitrogen, oxygen, carbon dioxide etc
5) CHROMATOGRAPHY
Defn: a method to separate and identify mixtures
Eg: separates dyes or colour from food/ ink/ pigments,check amounts of pesticides in vegetables, check if medicine contains banned drugs etc
(6) SUBLIMATION
Defn: a process in which substances changes from solid states to gaseous states through heating.
Eg: Ammonium chlorides ( NH4Cl ), dry ice ( solid CO2) ,naphthalene ( mothballs ), iodine
To test if a substance is pure / impure ( typical MCQ question!! )
CHECK IF IT HAS A FIXED BOILING / MELTING POINT------> IF IT IS PURE, IT WILL HAVE A FIXED MP/BP
Disclaimer: Picture are obtained from these websites-
GCSE Chemistry noteswww.wpbschoolhouse.btinternet.co.uk/page01/ElCpdMix/EleCmdMix.htm
